Company after company he visited turned out to be nothing like what they had held themselves out to be. He wound up selling all his positions and shorting several of those companies.

Shorting China frauds, however, is also "played out," in Buckley's view.

The obvious frauds have already been uncovered. There are very few public companies that are empty warehouses these days. Some questionable companies will no doubt be uncovered, but frauds in Chinese companies are now much harder to detect and it is less certain that they will eventually be exposed. (Read more: Holiday Gifts and China Graft Challenge)

So Buckley has turned to tech. Hence the title of his talk: it is 1999 all over again. There are tech companies that are severely overvalued, he argued. Their stock prices will fall.

Buckley singled out Splunk, a software platform company, as his short target. You can read about his argument against Splunk over at Business Insider. But what struck me as more interesting was this dynamic: the short-seller in search of the next overvalued sector.

We had real estate and home builders, then financial companies, then China. Now the young cool kids are turning against tech.